It is known generally known to store fluids under pressure in containers (cans or vessels) in a wide field of applications. The fluids are usually dispensed from the container by means of a valve arranged in a cup of the container.
A well-known application is sprayable foams used in both industrial applications and by hobbyists. As such, containers with sprayable foam can be exposed to rather extreme conditions in terms of temperature and pressure.
Under these extreme conditions, the pressure in the container may rise and the valve may detach from the container creating potential safety issues.
In order to prevent the above, several safety measures are used, such as providing an overpressure relief valve or providing “burst parts” in the container. However, the use of overpressure relief valves is expensive, while providing weakened “burst parts” in the container is no option for containers that are used on building sites as unintended burst of the container may be triggered by the nature of use of these containers.
Still, in order to prevent the valve from detaching from the container due to overpressure, it is possible to mould part of the grommet over the container cup. However, the overmoulding is a cost inefficient process.
It has now been found that the new valve of the present invention overcomes the above mentioned drawbacks.
The valve according to the present invention is a valve for a container, the valve comprising a grommet defining a channel with an inlet end and an outlet end; a stem, slideably arranged in said channel; the grommet comprising a first part provided at said inlet end and a second part provided at said outlet end, characterized in that the first part has a hardness greater than the hardness of the second part.
In addition, it has been found that the valve is sufficiently resilient while equally being moisture resistant thereby avoiding stickiness and blockage of the valve.
Use of dual plastic grommet in a valve for a container has already been disclosed in EP 1,606,195. The invention describes a valve comprising a grommet having at least one part made of non-thermoplastic rubber and another part made of a thermoplastic material. Although a thermoplastic material has been used to provide hydrophobic properties and avoid diffusion/absorption of ambient moisture in the container through the valve, thermoplastic materials exhibit other inconveniences such as “creep”, which is a well known property of thermoplastic (TP) rubbers. This creep allows for the materials to deform and causes the grommet to detach from the cup when the container is put under extreme pressure.
Given the above, the present invention provides a valve for a container dispensing a pressurized fluid and an assembly applied for dispensing of pressurized fluids with low creep properties and sufficient resilience while avoiding the use of an embedding or molding step and avoiding the necessity of using of a spring.
In addition, a valve is provided for a container dispensing pressurized fluids which valve is moisture repellent and therefore will inhibit the water diffusion and/or absorption that is causing stickiness and blockage of the valve.
None of the prior art discloses the valve according to the present invention nor do these documents suggest the presently obtained benefits associated therefrom.